In certain rotary engines, liquid cooling is provided in the side or end casings, and when multiple rotors are present, in the intermediate casing(s). In these engine casings, fluid cavities are provided to cool the rotor housings. However, the manufacturing of such engine casings can be complex and limited to specific manufacturing methods, such as casting. Moreover, since the casings have surfaces in sliding contact with the rotating rotors, wear and damage is inevitable. Yet, because of the cooling passages these can be expensive components to replace.